1. Field of the Invention
Through the recorded use of leveling devices, it has been difficult to read the device under low light conditions. This is especially so when the level is used in places where it is difficult or impossible to place an exterior light source into the level location and onto the level. Many devices have been developed to attempt to illuminate the spirit vials used in most levels. Usually the approach used is to utilize a lamp to throw light onto the outer surface of the container.
2. Description of the Related Art
U.S. Pat. No. 2,367,858 to T. W. Flynn on Jan. 23, 1945 shows an illuminated level having a lucite rod that conducts light from a light source to place light in the vicinity of a spirit level bubble glass.
U.S. Pat. No. 2,543,572 to C. A. Friberg on Feb. 27, 1951 describes an illuminated spirit level that has a battery recessed into a web portion of the level body. The battery powers a lamp near the spirit level to illuminate the spirit level. A manual switch is provided.
U.S. Pat. No. 2,790,069 to G. G. Alexander on Apr. 23, 1957 shows a lamp so placed as to illuminate all the spirit levels shown at the same time. The lamps are battery powered. A thumb screw is used to hold the battery in place and acts as a switch.
U.S. Pat. No. 2,825,144 to J. W. Warden, Sr., et al, on Mar. 4, 1958 describes an illuminated combination level that provides a lamp, a battery and a switch. The light illuminates the level tubes. The level is substantially transparent between the lamp and the level tubes.
U.S. Pat. No. 3,046,672 to H. S. Lace on Jul. 31, 1962 shows a level that includes a light and a switch for activating the light and illuminating the bubble elements whenever the level is held against a structural member. A manual switch is also provided.
U.S. Pat. No. 3,192,375 to E. P. Olson on Jun. 29, 1965 describes an illuminated level that has a lamp located between pair of liquid columns to illuminate the columns. A battery to power the lamp and a switch are situated within the web of the level frame.
U.S. Pat. No. 3,584,212 to W. Hansen on Jun. 8, 1971 shows an illuminated spirit level that has a plurality of light sources to illuminate level containers. There is a ball-type gravity switch to activate selective lamps depending on the orientation of the level. There is a manual switch to terminate power to the lamps.
U.S. Pat. No. 3,724,087 to S. A. Ostrager on Apr. 3, 1973 describes a spirit level with translucent spirit vial housings that allows the transmittal of light to the vials.
None of these patents reveal the apparatus described herein that has a light source such as an LED enclosed within the container.